KR101912938B1 - Ultra Rapid Hardening Blended Cement Using Industrial By-product and Method for Repairing a Concrete Pavement Using the same - Google Patents

Abstract

The present invention relates to a rapid hardening blended cement composition which proactively uses an industrial by-product and a repairing method for concrete pavement suitably using the same. The rapid hardening blended cement composition according to the present invention comprises: a bond material comprising 25 to 55 wt% of Ordinary Portland Cement Type 1, 15 to 35 wt% of Calcium Sulfoaluminate having fineness of 4000 to 6000 cm2/g, 10 to 25 wt% of anhydrous gypsum having fineness of 5500 to 7500 cm2/g, and 5 to 25 wt% of blast furnace slag powder having fineness of 6000 to 8500 cm2/g; a phosphate-based retarder; a water-soluble polymer; a lithium-based accelerator; and a naphthalene-based dispersant, wherein the bind material further comprises a cogeneration boiler ash having fineness of 6000 to 8500 cm2/g, a CaO content of 10 to 30 wt% and an SO3 content of 5 to 20 wt%. The repairing method for concrete pavement according to the present invention is a repairing method for concrete pavement using a rapid hardening blended cement composition wherein a deteriorated portion of a concrete pavement surface is removed and cleaned, thereafter, the portion is filled with mortar prepared by mixing the rapid hardening blended cement composition with aggregate and water and then, allowed to cure.

Description

TECHNICAL FIELD [0001] The present invention relates to a cement composition for ultra rapid mixing using an industrial by-product, and a method for repairing a concrete pavement using the same.

More particularly, the present invention relates to a cement composition for ultra rapid mixing and a method for repairing concrete using the cement composition. More particularly, the present invention relates to a method for repairing concrete blast cement compositions using industrial byproducts, The present invention relates to a novel ultra rapid-light mixing cement composition which can economically enhance resistance to chlorine ion penetration by appropriately using an admixture such as a phosphate retarder and the like, while assuring economic efficiency by actively using fine powder and cogeneration boiler ash.

Most rapid cement is used for urgent repair of concrete structures. Especially, it is advantageously used for urgent repair work on concrete roads that require rapid opening of roads. However, the concrete road is mostly deteriorated due to the corrosion phenomenon caused by the winter seasoning agent, and the deterioration of the concrete road is severely deteriorated, so that the road concrete is required to have a predetermined performance in terms of chloride ion penetration resistance. It is also necessary to improve the chlorine ion penetration resistance of the quick-speed cement used for emergency road repair mortar.

On the other hand, it is reported that the use of blast furnace slag for concrete improves the penetration resistance of chlorine ions. Therefore the case of using the slag is a backroom cured body tissue formed by the chloride ion (Cl ^-) and suppressing the penetration of, at the same time, 12-15% containing the aluminum oxide component to the blast-furnace slag fine powder (Al ₂ O ₃₎ acts to chloride ions (Friedel's salt: 3CaO · Al ₂ O ₃ .CaCl ₂ · 12H ₂ O) is easily formed to inhibit the penetration of chloride ions.

Most of the initial velocity around cements expensive calcium sulfo aluminate _{(CSA, 4CaO · 3Al 2 O} 3 · SO 3) and calcium aluminate _{(SA, CaO · Al 2 O} 3, 12CaO · 7Al 2 O 3, CaO · 2Al 2 (3CaOAl ₂ O ₃ · 3CaSO ₄ · 32H ₂ O) is produced in large quantities by using cement minerals and gypsum from the O ₃ series. Etring zeite is a cement hydrate of acicular cement when it is cured to a large extent and exhibits excellent strength in the early stage.

4CaO · 3Al ₂ O ₃ · SO ₃ + XCaSO ₄ + YCaO + ZH ₂ O ==> 3CaO · Al ₂ O ₃ · 3CaSO ₄ · 32H ₂ O

(4CaO · 3Al ₂ O ₃ · SO ₃ : calcium sulfoaluminate, XCaSO ₄ : supplied from gypsum, YCaO: supplied from limestone)

However, most of calcium sulphoaluminate (CSA) and calcium aluminate (CA) used in quick-setting cement are most expensive imported products and there are restrictions on active utilization. In addition, since it has insufficient resistance to penetration of chlorine ions, Latex resin and the like are utilized together to ensure chlorine ion penetration resistance. However, Latex resin shows excellent effect in securing resistance against penetration of chlorine ions, but it has a disadvantage that it lowers the initial strength of the quick-curing cement and is very expensive.

KR 10-1720504 B1 KR 10-1708357 B1 KR 10-1816756 B1

The present invention has been developed to improve the disadvantages of repairing concrete pavement using conventional quick-speed cement. It reduces the use amount of expensive calcium sulfoaluminate and anhydrite and reduces the use of latex powder, blast furnace slag fine powder and cogeneration boiler ashes There is a technical problem to provide a new ultra rapid light mixing cement composition and a concrete pavement maintenance method which can advantageously use the byproducts while securing an excellent chlorine ion penetration resistance economically.

In addition, the present invention provides a method of repairing concrete pavement which can secure initial work time and securing excellent initial strength, and can secure excellent workability and durability by using a mortar having greatly improved resistance to infiltration of chloride ions .

In order to solve the above-mentioned technical problems, the present invention provides a cementitious cement composition comprising 25 to 55% by weight of an Ordinary Portland Cement, 15 to 35% by weight of calcium sulfoaluminate having a powdery degree of 4000 to 6000 cm 2 / g, A binder composed of 10 to 25% by weight of anhydrous gypsum having a powdery viscosity of 5500 to 7500 cm < 2 > / g and 5 to 25% by weight of fine blast furnace slag powder having a powder degree of 6000 to 8500 cm & 0.01 to 1.0 part by weight of a phosphate-based retarder based on 100 parts by weight of the binder; 0.01 to 1.0 part by weight, based on 100 parts by weight of the binder, of a water-soluble polymer; 0.01 to 2.0 parts by weight of a lithium-based accelerator relative to 100 parts by weight of a binder; Wherein the binder has a powder content of 6000 to 8500 cm2 / g or more, a CaO content of 10 to 30% by weight and an SO3 content of 5 to 20% by weight, And 45 to 85 parts by weight based on 100 parts by weight of the blast furnace slag fine powder, based on 100 parts by weight of the blended cogeneration boiler ash. Sodium phosphate as a phosphate retarder, polyvinylpyrrolidone as a white polymer powder having a specific gravity of 1.23 to 1.29 and a pH (5% solution) of 5 to 8 as a water soluble polymer, lithium carbonate as a lithium promoter, As the naphthalene-based dispersing agent, a polynaphthalene sulfate powder can be preferably used.

Also, the present invention relates to a method for repairing concrete pavement using a cement composition having a very high initial speed, comprising the steps of: removing the deteriorated portion of the concrete pavement surface to remove the aggregated cement composition; And 40 parts by weight of water is added to the mortar to finish the concrete pavement repairing method.

According to the present invention, the following effects can be expected.

First, it is possible to provide a new ultrahigh speed cement mixed cement which can secure initial work time, secure initial strength, and greatly improve resistance to penetration of chlorine ions. Particularly, the present invention reduces the amount of expensive calcium sulfoaluminate or anhydrite used and does not use latex, and at the same time makes use of industrial by-products such as blast furnace slag powder and cogeneration boiler ash, .

Second, when mixed with cement mortar and aggregate and water, it is applied to the repair work of concrete pavement, it is possible to secure the initial proper working time and to perform the repair work while exhibiting excellent initial strength. In addition, the chlorine ion penetration resistance of the repaired area is greatly improved, thereby ensuring durable stability.

Fig. 1 is a photograph of a chlorine ion penetration resistance testing apparatus.

TECHNICAL FIELD The present invention relates to an ultra rapid mixing cement which utilizes industrial byproducts actively, and a concrete pavement repairing method using the same. The ultra-quick-mix cement according to the present invention is widely used as a main component of the binder, which is a by-product of blast furnace slag powder and cogeneration boiler ashes. In addition, a phosphoric acid retarder, a water- Is used at the same time.

In the ultra rapid mixing cement of the present invention, the binder is composed of one kind of Portland cement, calcium sulfoaluminate, anhydrous gypsum, blast furnace slag powder, and cogeneration boiler ash. The binder may be preliminarily mixed and prepared as a pre-mix binder, or it may be separately prepared and then mixed with an admixture or the like in the field.

The first type Portland cement is a basic binder that exhibits strength by coagulation and curing. Type 1 Portland cement is very cheap compared to calcium sulfoaluminate, which is used in 25-55% by weight of the total binder. When the amount is less than 25% by weight, other materials such as calcium sulfoaluminate are relatively inadequate to be economically viable. When the amount is more than 55% by weight, the amount of calcium sulfoaluminate or the like is lowered and the initial strength development is poor.

Calcium sulfoaluminate reacts with one kind of Portland cement and anhydrous gypsum to produce a large amount of ettringite, which contributes to the initial strength improvement. Calcium sulfoaluminate has an Al2O3 content of 32% by weight or more and a powderity of 4000-6000 cm2 / g. When the content of Al2O3 is low and the powderity is high, an appropriate reaction can be performed at an early stage, and initial strength development becomes possible. Calcium sulfoaluminate is used in an amount of 15 to 35% by weight of the total binder. When the amount is less than 15% by weight, initial strength development is poor. When the amount is more than 35% by weight, the cost is 6 to 10 times higher than that of one kind of Portland cement.

Anhydrous gypsum reacts with one kind of Portland cement and calcium sulfoaluminate to produce a large amount of ettringite, which contributes to the initial strength improvement. The anhydrous gypsum has a powdery degree of 5500 ~ 7500cm2 / g. The higher the degree of powder is, the more appropriate reaction can be made in the early stage, but if it is too high, the economic efficiency is lost. The anhydrous gypsum is used in an amount of 10 to 25% by weight of the entire binder in consideration of initial strength development and economical efficiency.

Blast furnace slag powder is used to secure chlorine ion penetration resistance with economic efficiency. In order to effectively induce chlorine ion penetration resistance while inducing the initial reaction effectively, a fine powder with a powder degree of 6000 ~ 8500 cm2 / g is used do. The blast furnace slag powder is used in an amount of 5 to 25% by weight of the total binder. If it is less than 5% by weight, the chloride ion penetration resistance effect is insignificant.

Combined cogeneration boiler ash not only contributes to the production of ettringite by economically supplying CaO and SO3, but also contributes to the reaction of blast furnace slag fine powder. The cogeneration boiler ash has a CaO content of 10 to 30 wt%, an SO 3 content of 5 to 20 wt% and a powder viscosity of 6000 to 8500 cm 2 / g or more so that an appropriate reaction can be performed at an early stage. Combined heat and steam boiler ash is preferably 45 to 85 parts by weight based on 100 parts by weight of the blast furnace slag fine powder in order to exhibit performance and workability.

In the ultra rapid mixing cement of the present invention, the admixture is composed of a phosphoric acid retarder, a water-soluble polymer, a lithium accelerator, and a naphthalene dispersant. The admixture may be preliminarily mixed with the binder as well as prepared as a pre-mix admixture, or may be mixed with a binder to prepare a pre-mix quick-mix cement. Further, it may be separately prepared and then mixed with a binder in the field.

Phosphoric acid retarder is a material for securing a stable reaction time in the early stage by suppressing excessive sharpening. In the case of conventional quick-speed cement, a tin-based or citric-based retarder is mainly used. However, when the blast furnace slag fine powder is used as in the present invention, the phosphoric acid retarder is effective and quickly recovered in strength. Sodium phosphate is preferably used as the phosphoric acid retarder, and 0.01 to 1.0 part by weight of 100 parts by weight of the binder is used. If the amount is less than 0.01 part by weight, the retarding effect is insignificant. If the amount is more than 1.0 part by weight, the initial strength development is delayed excessively.

The water-soluble polymer is dissolved in water during the mortar compounding process to partially coat the cement particles, thereby delaying the hydration reaction of the cement. If the moisture is removed as the mortar is dried / cured, the water-soluble polymer is also dried and the volume is reduced, and the coating area of the cement particles is also reduced. The water-soluble polymer is preferably a white powder of polyvinylpyrrolidone having a specific gravity of 1.23 to 1.29 and a pH (5% solution) of 5 to 8, preferably 0.01 to 1.0 part by weight based on 100 parts by weight of the binder. If the amount is less than 0.01 part by weight, the retarding effect is insignificant. If the amount is more than 1.0 part by weight, the hydration reaction of the cement is excessively delayed to cause a decrease in strength.

Lithium-based accelerator is the most reliable strength promoter in ultra fast cement. It has a very high limit. However, when it is used in a large amount, it is difficult to secure the working time and it may cause a decrease in strength. In view of this, the amount is preferably 0.01 to 2.0 parts by weight based on 100 parts by weight of the binder. The lithium-based promoter preferably uses lithium carbonate.

The naphthalene-based dispersing agent contributes to securing the strength by reducing the mixing water as well as ensuring proper workability through the dispersing effect. The naphthalene-based dispersant is preferably a powder of polynaphthalene sulfate and is used in an amount of 0.2 to 1.5 parts by weight based on 100 parts by weight of the binder. If the amount is less than 0.2 part by weight, the dispersing effect is insignificant. If the amount is more than 1.5 parts by weight, there is a fear of loss of economical efficiency and initial strength reduction.

The above-mentioned quick mix blended cement composed of a binder and an admixture can be advantageously used for urgent maintenance of concrete pavement by mixing it with mortar and water together with mortar. Since the initial work time is secured and the initial strength is excellently developed, it is possible to smoothly carry out repair work on the concrete pavement, and furthermore, after completion of the repair work, it is possible to greatly improve the resistance to chlorine ion penetration at the repair site, Lt; / RTI > However, it is preferable to mix the aggregate in an amount of 80 to 300 parts by weight and the water in an amount of 20 to 40 parts by weight based on 100 parts by weight of the binder in consideration of economical efficiency, workability, It is preferable to use silica sand having a moisture content of 5% or less.

Concrete pavement repair work should be carried out according to the usual method. For example, after removing the deteriorated part of the concrete pavement, it is finished by charging the repair mortar. In this case, it is possible to apply the concrete performance remover to the cleaning part before charging the mortar, thereby inducing the recovery of the performance of the concrete or improving the adhesion between the charging mortar and the primer.

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples. However, the following Examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

[ Test Example  1] Mixed Cement Composition

(1) Binder composition

A binder was prepared in the same composition as in Table 1 below.

Binder composition (% by weight) Constituent material Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Example 1 A 51 41 44 41 41 36.7 36.7 B 32 32 30 32 32 28.6 28.6 C 17 17 16 17 17 16.3 16.3 D - 10 10 - - - - E - - - 10 10 11.6 11.6 F - - - - - 6.8 6.8 sub Total 100 100 100 100 100 100 100

In Table 1, A is a type 1 Portland cement, B is calcium sulfoaluminate having a powder degree of 4,600 cm 2 / g, a specific gravity of 2.8 and an Al 2 O 3 content of 36% by weight, C has a powder degree of 6120 cm 2 / D is a blast furnace slag having a specific gravity of 4080 cm2 / g and a specific gravity of 2.91, E is a blast furnace slag having a fineness of 6270 cm2 / g and a specific gravity of 2.90, F is a slag finite powder having a fineness of 6130 cm2 / g, specific gravity of 2.92, CaO content of 11.8 wt% and SO3 content of 5.9 wt%.

In Comparative Example 1 and Comparative Examples 2 and 3, there was a difference in mixing of blast furnace slag fine powders. In Comparative Examples 2 and 3 and Comparative Examples 4 and 5, there were differences in kinds (blast furnace) of blast furnace slag powder, , 5 and Comparative Example 6 and Example 1 differ in whether or not the cogeneration boiler ash is mixed.

(2) Composition of admixture

An admixture was prepared with the composition shown in Table 2 below.

(Parts by weight relative to 100 parts by weight of the binder in Table 1) Constituent material Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Example 1 G 0.3 0.3 0.3 0.3 - 0.3 - H - - - - 0.4 - 0.4 I - - - - 0.03 - 0.03 J 0.15 0.15 0.15 0.15 0.15 0.15 0.12 K 0.5 0.5 0.5 0.5 0.5 0.5 0.5

In Table 2, G is tartaric acid, H is sodium phosphate, I is polypyrrolidone having a specific gravity of 1.24 and pH (5% solution) of 6.8, J is lithium carbonate, and the naphthalene dispersant is a polynaphthalene sulfate powder to be. In Comparative Examples 1 to 4, 6, Comparative Example 5 and Example 1, there is a difference in mixing of tartaric acid, sodium phosphate and polypyrrolidone.

[ Test Example  2] Mortar formulation and performance test

1. Mortar formulation

Mortar was formulated with 115 parts by weight of aggregate and 31 parts by weight of water based on 100 parts by weight of the binder together with the binder and admixture prepared above.

2. Mortar performance

(1) Test method

The mortar mixed was tested for compressive strength, setting time, flow and resistance to chlorine ion penetration. The compressive strength was measured by molding the specimen (mold of 40 × 40 × 160 mm size, curing at constant temperature and humidity (temperature 20 ± 2, humidity 90% or more)) according to KS L ISO 679 And 2 hours, 4 hours, 7 days, and 28 days of age. The setting time was tested by KS L ISO 9597 (Cement Condensation and Stability Test Method).

The flow was carried out in accordance with the KS L 5105 (Compressive Strength Test Method for Hydraulic Cement Mortar). The molding frame was placed on the electric flow test table, the mortar was twisted 20 times, the upper surface was flattened with trowel, The mold was immediately taken out and mortar was hit for 15 seconds for 25 times and the diameter of the mortar was measured.

Chloride ion penetration resistance was measured according to KS F 2711 (Concrete Chloride Ion Penetration Resistance Test by Electrical Conductivity). The specimens used for the test were cured for 28 days in a Ø100 × 200 mm specimen, and then the specimens were cut so as to be Ø100 × 50 ± 3 mm. These test pieces were fixed to the test cell as shown in Fig. 1, and a circuit was constituted to measure the total length and charge amount of each test piece.

(2) Test results

The performance test results of the mortar are shown in Table 3 below.

Mortar performance division Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Example 1 Condensation time (seconds, minutes) 14 18 19 Sharp 14 Sharp 15 Flow (mm) 215 220 220 Not measurable 215 Not measurable 220 2 hours Compression strength (MPa) 28 17 14 Can not be formed
(Measurement impossible) 15 Can not be formed
(Measurement impossible) 27 4 hours Compressive strength (MPa) 36 21 16 20 38 7 days Compressive strength (MPa) 48 42 43 43 56 28 days Compressive strength (MPa) 62 60 58 58 67 Chloride ion penetration resistance
(coloumb) 3,120 2,530 2,450 950 760

Rapid-speed cement generally requires a curing time of 10 minutes or more, a compressive strength of 25 MPa or more for 2 hours, and a chlorine ion penetration resistance of 1,000Coloumb or less.

Comparative Example 1 is an example of a mortar using conventional conventional quick-curing cement, but it did not satisfy the requirement because the chlorine ion penetration resistance was 3,000 Coloumb. Chloride ion penetration resistance requirements are usually solved by incorporating Latex resin. However, when Latex resin is mixed, it can secure 800 ~ 1,000Coloumb level, but there is a drawback that the cost is very high.

In Comparative Examples 2 and 3, instead of cement, the fine powder of blast furnace slag having a particle size of 4000 to 4500 cm 2 / g was partially substituted, and as shown in the figure, resistance to chlorine ion penetration was not significantly improved, Respectively.

In Comparative Example 4, the blast furnace slag powder was used in Comparative Examples 2 and 3 at a powder level of 6000 cm < 2 > / g.

In Comparative Example 5, sodium phosphate and polypyrrolidone were used instead of tartaric acid as a retarding agent in Comparative Example 4, indicating that the initial strength was greatly reduced even though the sharpness was alleviated and the chlorine ion penetration resistance also met the required level.

Comparative Example 6 is a case in which a cogeneration boiler ash was further used in Comparative Example 4, but a sudden phenomenon occurred.

In Example 1, in the case of using the cogeneration boiler ash (the blast furnace slag powder of 6000 cm 2 / g level, the cogeneration boiler ash, the phosphoric acid retarder and the water-soluble polymer) in the comparative example 5, It was shown that the initial strength was excellent and the chlorine ion penetration resistance was greatly improved. Particularly, in Example 1, compared with Comparative Example 1, industrial byproducts are utilized in a large amount. Therefore, according to the present invention, it is possible to manufacture a cement composition having a very high initial speed.

Claims (3)

delete 15 to 35% by weight of calcium sulfoaluminate having 25 to 55% by weight of Ordinary Portland Cement, 4 to 6,000 cm 2 / g of powder, and an anhydrous gypsum having a powdery degree of 5500 to 7500 cm 2 / g 5 to 25% by weight of a blast furnace slag powder having 10 to 25% by weight and a powdery degree of 6000 to 8500 cm2 / g;
0.01 to 1.0 part by weight of a phosphate-based retarder based on 100 parts by weight of the binder;
0.01 to 1.0 part by weight of a water-soluble polymer based on 100 parts by weight of the binder;
0.01 to 2.0 parts by weight of a lithium-based accelerator relative to 100 parts by weight of the binder;
0.2 to 1.5 parts by weight of a naphthalene dispersant based on the weight ratio of the binder 100;
≪ / RTI >
The binder may further include 45 to 85 parts by weight of cogeneration boiler ash having a powdery degree of 6000 to 8500 cm2 / g, a CaO content of 10 to 30% by weight and an SO3 content of 5 to 20% by weight based on 100 parts by weight of the blast furnace slag fine powder ≪ / RTI >
The phosphate retarder is sodium phosphate,
The water-soluble polymer is a white powder of polyvinylpyrrolidone having a specific gravity of 1.23 to 1.29 and a pH (5% solution) of 5 to 8,
The lithium-based accelerator is lithium carbonate,
Wherein the naphthalene-based dispersant is a polynaphthalene sulfate powder. A method for repairing concrete pavement using the ultra rapid mix cement composition according to claim 2,
After removing the deteriorated part of the concrete pavement and cleaning it,
Wherein the mortar mixed with 80 to 300 parts by weight of aggregate and 20 to 40 parts by weight of water is blended with the initial curing composition to complete the concrete pavement repairing method.

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